PHP object return false if no properties - php

Question

I am trying to make a class what will contain a set of properties. it will be used like so:
$class = new test_class();
$class->property;
$class->second_property;
Basically, if the properties exist, then they are true, if the properties do not exist, they are false. The properties have no value, only existence.
Now, I want to do something like this:
$class = new test_class();
var_dump($class->property); // false - property does not exist
var_dump($class->second_property); // true - second_property exists
var_dump( (bool) $class); // true
So if even one property of the test class exists, var dumping the $class will show true because it is an object.
However, in the situation where the class has no properties, I want this to happen:
$class = new test_class();
var_dump($class->property); // false - property does not exist
var_dump($class->second_property); // false - second_property does not exist
var_dump( (bool) $class); // false
But, I still want $class to be instanceof the test_class but return false in a logic test.
Is this at all possible? If so, how would I do it?
Thanks, Ozzy
edit:
To clarify, I am already using the __get() magic function. What I want to happen is if the test_class has no properties, then when a var_dump is performed on it, it returns false but an instanceof will return test_class.
elaborating...
I am creating a complex permissions system.
A user gets assigned sections and each section has a set of permissions.
It will work like this:
$user = permissions::get_user(USER_ID_HERE);
// Every property of the $user is a section
var_dump($user->this_section_exists); // true - returns an object
var_dump($user->this_section_doesnt); // false - returns a boolean
If a section exists, then it returns an object of the sections permissions.
var_dump($user->this_section_exists); // true
var_dump($user->this_section_exists->this_permission_exists); // true
var_dump($user->this_section_exists->this_permission_doesnt); // false
Heres the edge case:
var_dump($user->this_section_doesnt); // false
var_dump($user->this_section_doesnt->some_permission);
// This should also return false, which it does,
// But it throws a notice: "Trying to get property of non-object"
I want to be able to either suppress that notice without any modifications to the code which calls the class, ie, no # to suppress.. or be able to return an object with no properties which evaluates to false on a logic test.

Answer 1

What I want to happen is if the test_class has no properties, then when a var_dump is performed on it, it returns false but an instanceof will return test_class.
That is not possible, var_dump will always show you the correct type, that's what it was made for.

Answer 2

No, you can't do it exactly as you wrote it. But you can emulate something similar:
class A {
public function __toString() { // this is what you want, but it only works when you use your object as a string, not as a bool.
if (count(get_class_vars(__CLASS__))) { // so if the class has at least 1 attribute, it will return 1.
return '1';
} else {
return '0';
}
}
}
$a = new A;
var_dump((bool)(string)$a); // false
If I add a propery in A class it will return true. You can also use it without (bool).
if ((string)$a) {
echo 'I am not empty';
} else {
echo 'I am an empty object';
}
If you don't want to use (string), you have one option left, to create a method that contains the code from __toString() and call it instead of casting.
References:
__toString()
get_class_vars()
__CLASS__
PS: About what you said - doing a var_dump() on the object to return false. No, that is not possible.

Answer 3

You can do some wrapping with __get() to manipulate the answer.
Say something like
class test_class {
private $_validProperties;
public function __construct()
{
$this->validProperties = array('foo', 'bar', 'widget');
}
public function __get($prop)
{
if (isset($this->_validProperties[$prop])
{
return true;
}
return false;
}
}
$a = new test_class();
var_dump($a->foo); //true
var_dump($a->tree); //false

Answer 4

You can try PHP magic function
<?php
class Test {
private $name = 'name';
public $age = 20;
public function __get($name) {
return isset($this->$name) ? true : false;
}
public function __toString() {
return true;
}
}
$object = new Test();
var_dump($object->name); // output `true`
var_dump($object->age); // output `20`
var_dump($object->notfound); // output `false`
var_dump((bool)$object); // output `true`

Answer 5

If I understand you correctly, I can only do so.
Hope it can help you
<?php
class Permissions {
private $userPermissions = array(
1 => array(
'Blog' => array('Post'),
),
);
private $permission;
public function __construct($id) {
$this->permission = $this->userPermissions[$id];
}
public function __get($name) {
if(isset($this->permission[$name])) {
return new $name($this->permission[$name]);
}
return new Notfound();
}
}
class Blog {
private $permission;
public function __construct($permission) {
$this->permission = $permission;
}
public function __get($name) {
if(($key = array_search($name, $this->permission)) !== false) {
return new $name();
}
return new Notfound();
}
public function __tostring() {
return true;
}
}
class Post {
public function __get($name) {
return isset($this->$name) ? true : new Notfound();
}
public function __tostring() {
return true;
}
}
class Notfound {
public function __get($name) {
return false;
}
public function __tostring() {
return false;
}
}
$user = new Permissions(1);
var_dump('Blog ', $user->Blog); // return Blog
var_dump('Blog:Post', $user->Blog->Post); // return Post
var_dump('News', $user->News); // return Notfound
var_dump('News:Post', $user->News->Post); // return false